86 
tuents contained in the fuel but the compound which is formed 
with sufficient heat in the process of combustion that acts as the 
real re-agent and coagulates latex ; that volumes or clouds of 
smoke are not only unnecessary but are* positively harmful ; that 
a smoke house should be well ventilated and the temperature kept 
as low as possible; that the furnace or heat should always be 
generated outside the smoke house ; that smoke from a furnace should 
never go direct on latex or rubber; that fuel (wood or coconut husk) 
be always dry in view of furnishing comparatively dry smoke; 
that all smoke be passed through the furnace chimney until the fire 
is established or burnt through and the temperature very high ; that 
the fire is well stoked and not choked with too much fuel or allowed 
to fall too low. 
17. How these various items are arranged in the apparatus I 
am exhibiting will be explained, but I wish to pause here to emphasise 
the importance of maintaining a regular supply of smoke from a well 
consumed fire. Of all the constituents contained in wood-fuel water 
is the most troublesome. However perfect the combustion water- 
vapour has to be disposed of, and excess smoke-vapour results in 
condensation within the house and a steamy atmosphere which is 
fatal to good coagulation. (The fat and oil ever present on superfi- 
cially-smoked biscuits and sheets is really a deposit of wood naptha- 
line and other impurities conveyed by excess vapour in smoke due 
to wet fuel and the smoke passing direct on to the rubber — an error 
easily avoided). In the process of coagulation it is essential that the 
evaporation of water within the thin layers of latex shall be commen- 
surate with the heat supplied (not a high temperature at which 
caoutchouc perishes), and this cannot occur in an atmosphere sur- 
charged with steam or vapour, and the result is, the water and 
caoutchouc coalesce and the resulting rubber is uncured. 
18. The real problem of the treatment of Hevea latex is one of 
separation between the water and caoutchouc. With Castilloa and 
some other latices which contain an acid reaction this can be done 
by centrifugal motion at high speed, the caoutchouc separates into 
a mass and can be skinned off. With Hevea latex however, although 
remarkably flocculent — perhaps more so in Malaya than in South 
America — -such methods are futile. Hevea latex is alkaline to litmus 
and the process of coagulation, whether with or without a re-agent r 
is really one of coalescing into an agglutinated mass and the variable 
water residuum, is I suspect, more the result of pressure than separa- 
tion or precipitation of caoutchouc. (Under normal conditions Hevea 
latex coalesces by natural means satisfactorily if placed in a cylinder of 
which the height is three or four times that of the diameter and the water 
residuum is about the same as when treated with a re-agent such as acetic 
acid. In certam phases of the Hevea tree, at the time of this writing,. 
29-1-1912, all the latex in a cylinder 7 ins. by 2% ins. coalesced in fifteen 
hours without leaving a drop of fluid. Such re-agents as acetic-acid 
It is paradoxical. Volumes or clouds of smoke imply excess water-vapour. 
